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304 Stainless vs Aluminum

22 Feb 2021 4 Comments

There are several reasons why we came out with a stainless steel line. The main reason is that 304 stainless will offer the best level of protection against thieves and galvanic corrosion. We've tested our stainless steel shields against the best blades on the market and all the blades failed. Diablo carbide tip blades with a Milwaukee sawzall is no match for our stainless steel line. A thief will need multiple blades to even have a shot at cutting off the shield. No other manufacturer is committed to this high end material and it will certainly give you an extra peace of mind. 

We know not everyone will be able to afford the stainless steel shields. 9 times out of 10, simply having a shield is a great step in deterring thieves from stealing your converter since they will see a shield and likely move on. The aluminum shield is great to give you that initial deterrence. 

Whether you choose a stainless steel or aluminum shield, you will not need to worry about overheating. Our products are tested to ensure there are no adverse impact to your converters.

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Here are a few facts about stainless steel and aluminum. Check out our stainless steel line here.

- Strength, density, weight. Stainless steel has about twice the tensile strength of aluminum, making it harder to cut, bend, and warp. It is about 2.5 times more dense than aluminum and about three times as heavy. Our stainless shields are about twice as heavy as our aluminum ones depending on the application (4lbs vs 2lbs). 

- Corrosion. While both stainless steel and aluminum have anti-corrosive properties, we use zinc-coated rivet nuts to protect against galvanic corrosion. Whenever there is a drilled hole in the steel frame of the vehicle, the frame looses its protective coating and can accelerate corrosion. Whenever possible, we design our shields without drilled holes, but whenever our products need a drilled hole, we protect the vehicle with our zinc-coated rivet nuts. 

- Thermal properties. In temperatures of excess of 400 degrees, aluminum becomes very soft. If you encase a converter in aluminum, you will easily reach these temperatures. Our aluminum designs ensure the shields are adequately ventilated and tested to make sure they do not cause excessive build up of heat.

- Thermal conductivity. Aluminum has a better thermal conductivity than steel. This means that aluminum will heat up quicker than steel. However, neither materials will impact the temperatures around the converter due to our heat ventilation features.

Miller CAT Cat Shield vs Milwaukee Sawzall and Diablo Carbide Tip Blades


Is stainless steel 304 magnetic?

No, 304 stainless steel is not magnetic. Its austenitic microstructure is responsible for this. Austenite forms at high temperatures and usually reverts to the ferritic microstructure during the cooling process. The ferritic microstructure is magnetic. However, 304 stainless steel is alloyed with nickel, stabilizing the austenitic microstructure and enabling it to remain intact during the cooling process. That is how we can have a non-magnetic austenitic microstructure at room temperature.

304 stainless steel has a slight susceptibility to magnets, but this is not strong enough to be considered magnetic. Note that any process that this metal undergoes that changes its microstructure to ferritic will render it more magnetic.

Which types of stainless steel are magnetic?

Below are a few examples of magnetic and non-magnetic:

Ferritic stainless steel grade 430 is magnetic

The austenitic stainless steel grade 304 is not magnetic but it may become a little magnetic in areas that have been cold working (bending, deforming, etc.).

Austenitic stainless steel grade 316 is not magnetic

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28 Dec 2022 Willie Bee

Thieves have stolen the catalytic converters out of my 2009 Prius THREE TIMES since June 2022. State Farm will not help me on my claim this time without doubling my insurance premium. So, yes, insurance companies should offer a discount. I’ll mention this to my agent, for all the good that it’ll do.

20 Dec 2021 Al B.

To: whom it may concern,

I agree with Kory that your sales would increase if you could get insurance companies to offer a discount based on having your product installed on our autos!

Having statistics provided by local or state law enforcement supporting a reduction in theft by having a catalytic converter guard would help all of us in the long run.

Having the option to have your vin # either painted on or etched by the installer for a fee would also help reduce the chance that a recycler or junk yard would buy one from a questionable source.

31 Mar 2021 Prius Driver

When can we expect a stainless steel version to be available for Prius 2004-2009 Gen 2?

31 Mar 2021 Kory Trebbin

The insurance companies don’t know about your product especially State Farm let them know!!

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